The invention relates to a disc brake, particularly for vehicles, having a stationary housing, at least one friction or brake lining which, when the brake is actuated, can be displaced with respect to the housing, a lever device with a shaft which can be rotated about a first axis fixed with respect to the housing, the shaft carrying an eccentric, and an actuating lever or rotating lever being fastened to the shaft in such a manner that it extends essentially perpendicularly to the first axis. As a result of the rotation of the shaft about the first axis, the brake can be actuated which is triggered by the pressure on the rotating lever, a pressure member or eccentric follower, which can be displaced within the housing along a second axis which extends essentially perpendicularly to the first axis. The follower rests with its first end on the eccentric and with its second end acting with respect to the brake lining: means are provided for adjusting and absorbing wear which increases the distance separating the first axis from the second end of the follower as a function of the wear of the brake lining.
A disc brake of this type is described, for example, in French Patent Document FR-A-2,548,309.
Disc brakes of this or a comparable type are known to a person skilled in the art; thus, with respect to the problem of providing a simple construction while the weight is low and the size is small.
With respect to all efforts of achieving these objects, the advantages of the simple construction and of the low weight or weight reduction, are countered by the requirements of a sturdy construction and a reliable operation.
Based on the above, it is an object of the present invention to provide a simple brake of the discussed type which has small dimensions and is nevertheless resistant in order to be suitable for being used in commercial vehicles.
For achieving this object, the brake according to the invention is distinguished by the following characteristics:
The eccentric has two bearing sections arranged on either side of the rotating lever;
on the one hand, the eccentric follower has, on the side of its first end, a nut with a central threaded bore as well as two essentially semicylindrical lateral bearing shells which are used for receiving the corresponding bearing sections of the eccentric; PA1 on the other hand, the eccentric follower has a screw whose first end engages the nut, while a second end of the screw forms the second end of the eccentric follower or the pressure member; and PA1 the means for adjusting the wear generate a relative rotation of the screw and of the nut whereby the eccentric follower or pressure member can be extended. PA1 the screw extends by an amount which corresponds to at least a minimal wear condition of the brake lining over the threaded bore situated in the center, on the side facing the shaft; and PA1 in the position facing the threaded bore of the nut, the shaft has a recess for receiving the screw if this screw extends beyond the central threaded bore.
According to a preferred embodiment of the invention which contributes to obtaining a brake of very small dimensions, the following characteristics are provided:
The rotatable lever arrangement with the eccentric is manufactured in one piece;
Preferably, the disc brake is constructed such that a bore is entered into the shaft in the direction of the first axis. The means of adjusting the wear, at least on one side, have a first pinion which is situated in this bore and is connected with the shaft in a partially rotatable manner, as well as a second pinion which engages with the first pinion and extends in the screw along the second axis. In which case, the second pinion is rotatably connected with this screw, and the screw can be displaced with respect to the second pinion along the second axis.
In order to permit a manual adjusting of the brake, particularly in the case of an exchange of the brake lining, the arrangement is such that the first pinion contains a spindle which extends beyond the bore of the shaft through the housing in such a manner that a torque can be applied from outside the housing.
Furthermore, the second pinion and the screw are rotatably connected by a kinematic chain with the shaft of the rotatable lever device. The kinematic chain contains a free wheel and a torque limiting device, and the free wheel has an outer cage and an inner cage which are connected with one another only in one rotating direction.
According to a first embodiment of a means for adjusting the wear, the outer cage of the free wheel is arranged in the bore of the shaft and is rotatably fastened thereto. The torque limiting device also is constructed in the bore of the shaft, and by way of this torque limiting device, the first pinion is rotatably connected with the inner cage of the free wheel.
A second embodiment of the means for adjusting the wear according to the invention provides that the outer cage of the free wheel is constructed in the bore of the shaft and is rotatably connected therewith. The inner cage of the free wheel is rotatably connected with a third pinion which is situated coaxially and outside the first pinion and meshes with a fourth pinion which is situated in the screw coaxially to the second pinion and outside thereof. The torque limiting device is arranged in the screw and is functionally connected between the fourth pinion and this screw.
A third embodiment of the means for adjusting the wear of the disc brake according to the invention provides that a third pinion is situated coaxially and outside the first pinion inside the bore of the shaft and is rotatably connected therewith. This third pinion meshes with a fourth pinion which is situated in the screw coaxially with respect to the second pinion and outside thereof. The free wheel and the torque limiting device are constructed inside the screw and rotatably connect the fourth pinion with the second pinion and with the screw.
The torque limiting device may correspond to a spherical construction which is known per se.
Preferably, the bearing of the shaft is constructed such that, on both sides of the bearing sections of the eccentric, it has two additional bearing sections whose axes extend along the first axis and by means of which the shaft of the rotatable lever devices is carried by the housing. This arrangement permits a further reduction of the constructional dimensions of the brake according to the invention in the direction of the first axis to such an extent that the shaft can be disposed in the housing outside the effective area between the eccentric and the nut.